Long-time stable water-repellent and oil-repellent surface

ABSTRACT

The present invention relates to a long-time stable, hydrophobic or oleophobic surface and to the use thereof.

[0001] This invention relates to a long-term stable water-repellentand/or oil-repellent surface and its utilisation.

[0002] For purposes of the invention, a water-repellent material is amaterial which, on a flat, non-structured surface, exhibits a boundaryangle in relation to water of greater than 90°.

[0003] An oil-repellent material for purposes of the invention is amaterial which, on a flat, non-structured surface, exhibits a boundaryangle in relation to long-chain n-alkanes, such as n-decane, of greaterthan 90°.

[0004] Such surfaces can, for example, be used on windows in cars, ifthey are simultaneously transparent. In rain, the water-repellentproperty leads to the formation of droplets which can be removed by theslipstream, thus greatly improving visibility in rain.

[0005] Consequently, there have been many attempts to make suchwater-repellent and oil-repellent surfaces available. For example, inthe publication by A. Hozumi, H. Sekoguchi, N. Kakinoki and O. Takai inJournal of Materials Science 32, 4253-4259 (1997), there is described aprocess by means of which transparent substrates are coated with a thintransparent water-repellent film. The film is produced byradio-frequency-supported CVD (chemical vapour deposition) ofperfluoroalkyl compounds, and produces a water boundary angle of 107°.

[0006] Furthermore, the teaching of U.S. Pat. No. 5,688,864 (Patentholder: PPG Industries), indicates how glass surfaces can be renderedwater-repellent using perfluoroalkyl silanes. For this purpose, thecompound is applied in a solvent to the glass surface, in which processthere is reaction between the silane and the surface. After treatment,the silane has a water boundary angle of 115°.

[0007] However, surfaces produced by means of this process suffer fromthe disadvantage that the contact angle of a droplet residing on thesurface will greatly decrease over a period of time. Consequently,efforts have frequently been made to extend the durability of thewater-repellent coating. The teaching of U.S. Pat. No. 5,980,990 in thiscontext is that pre-treatment of the glass surface with an acid,followed by reaction with a water-repellent silane, will producemarkedly improved long-term stability.

[0008] However, the durability of these films is restricted to a fewmonths under normal use. PPG Industries for example recommends, in itsoperating instructions for its Aquapel® product which is described asbeing very durable, that the coating should be renewed after a fewmonths, under normal use.

[0009] From this we derived the task of making available water-repellentand/or oil-repellent surfaces and processes for their production whichexhibit a contact angle >90°, which remain stable over many years, evenunder heavy loading.

[0010] In accordance with the invention, this function is achieved bythe production of a surface which is described for purposes of examplein FIG. 1. On a carrier (e.g. glass or a polymer such as polycarbonate)there is a reservoir coating in which a repellent agent is dissolved andfreely moveable, which is water-repellent and/or oil-repellent. Afurther coating (covering coating) covers the reservoir coating inrelation to outside. Through pores in the covering coating, therepellent agent in the reservoir coating will diffuse to the outersurface, where it will create an outer coating. The surface of thiscoating exhibits a boundary angle >90° in relation to water.

[0011] The subject of the invention is a long-term stablewater-repellent or oil-repellent surface constructed at least from asubstrate with a reservoir coat arranged on it, which contains arepellent agent, a covering coating arranged over it and having pores,or being permeable to the repellent agent, and an outer coat which ismade up of the repellent agent.

[0012] In the case of surfaces according to prior art, thewater-repellent coat is slowly broken down, for example, due toweathering. This greatly limits its useful life. Under this invention,it was, however, surprisingly found that fresh repellent agent wascontinuously supplied for the outer coating through the pores, whichconsistently precisely compensated for the breakdown, provided thatmaterial was still present in the reservoir coating. The boundary anglealso remains stable thanks to the supply of fresh repellent agent.

[0013] The surface of the covering coating particularly advantageouslyexhibits a surface topography as defined in the international patentapplication whose case reference is PCT/99/10322. Surface topography isconstructed such that the value of an integral of a function S

S(log f)=a(f)·f

[0014] which states a relationship between local frequencies f of theindividual Fourier components and their amplitudes a(f), betweenintegration limits log(f₁/μm⁻¹)=−3 and log(f₂/μm⁻¹)=3, is at least 0.3.

[0015] In this case, the boundary angle in relation to water is markedlyhigher than that of a non-structured, flat surface.

[0016] The reservoir coating preferably has a thickness in the range of0.1 μm to 10,000 μm particularly preferably in the range of 1 μm to2,000 μm, quite particularly advantageously in the range of 10 μm to1,000 μm and especially advantageously in the range of 50 μm to 500 μm.

[0017] Preferably, the covering coating has a thickness in the range of0.01 μm to 100 μm, preferably in the range of 0.021 μm to 50 μm,particularly preferably in the range of 0.05 μm to 20 μm and quiteespecially preferably in the range of 0.1 μm to 10 μm.

[0018] The pores 4 can exhibit in transverse section along theirlongitudinal axis a cylindrical or conical form or any other desiredform. At the boundary surface to the reservoir coating, which mayindependently be the same or different at the boundary surface inrelation to the outer coating of 10⁻⁵ μm² up to 10⁶ μm², preferably of4×10⁻⁴ μm² to 4×10⁴ μm², particularly preferably from 1×10⁻² μm⁻² up to1×10⁴ nm² and quite exceptionally advantageously from 2×10⁴ μm² to 2×10³μm².

[0019] The number of pores per surface is in particular from 2 mm⁻² to10⁻⁴ mm⁻², preferably from 1 mm⁻² to 10⁻³ mm², and particularlyadvantageously from 0.5 mm⁻² to 10⁻² mm⁻².

[0020] The pores are preferably produced by ablation with lasers,particularly preferably using ultraviolet laser, and quite exceptionallypreferably produced by ultraviolet laser in the wavelengths of 308 nm,266 nm, 248 nm, 213 nm, 193 nm or 157 nm.

[0021] In a further preferred method, pores 4 are produced bylithography using masks with chemical etching methods.

[0022] The substrate consists of any desired material which can becoated for water-repellent and/or oil-repellent properties. Thesubstrate preferably consists of a transparent material, especiallytransparent glass, plastic or ceramics.

[0023] The reservoir coating is in particular an open/porous coating ofmetal or an open/porous coating of a ceramic material, or consists of aduroplastic or thermoplastic synthetic material. Preferably, thereservoir coating consists of a transparent material, particularlytransparent glass, plastic or ceramics.

[0024] A particularly preferred metal to be selected for the reservoircoating and/or the substrate can be taken from the following range:beryllium, magnesium, scandium, titanium, vanadium, chromium, manganese,iron, cobalt, nickel, copper, zinc, gallium, yttrium, zircon, niobium,molybdenum, technetium, ruthenium, rhenium, palladium, silver, cadmium,indium, tin, lanthanum, cerium, praseodymium, neodymium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, lutecium, hafnium, tantalum, tungsten, rhenium, osmium,iridium, platinum, gold, thallium, lead, bismuth, particularly titanium,aluminium, magnesium, nickel or any possible alloy of the abovementioned metals.

[0025] Metal oxides, metal carbides, metal nitrides, metal sulphides,metal fluorides of the above-mentioned metals, and compounds of thesematerials, are particularly suitable as ceramic materials for thereservoir coating and/or the substrate.

[0026] The preferred duroplastic synthetic material can be obtainedparticularly from the following range: diallylphthalate resin, epoxyresin, uric acid-formaldehyde, melamine formaldehyde resin, melaminephenol formaldehyde resin, phenol formaldehyde resin, polyamide, siliconrubber and non-saturated polyester resin.

[0027] The preferred thermoplastic synthetic material is selected inparticular from the following range: thermoplastic polyolefin, e.g.polypropylene or polyethylene, polycarbonate, polyester carbonate,polyester (e.g. PBT or PET), polystyrene, styrene copolymer, SAN resin,styrene graft copolymer, e.g. ABS polymer, polyamide, polyurethane,polyphenylene sulphide, polyvinyl chloride or any possible mixtures ofthe above mentioned polymers.

[0028] In particular, the following thermoplastic polymers are suitableas substrates for the surface as per the invention:

[0029] Polyolefins such as high and low density polyethylene, e.g.densities from 0.91 g/cm³ to 0.97 g/cm³, which can be produced accordingto known processes, Ullmann (4.) 19, pages 167 and following pages,Winnacker-Kückler (4.) 6, 353 to 367, Elias & Vohwinkel, Neue PolymereWerkstoffe für die industrielle Anwendung, (New polymer materials forindustrial applications), Munich, Hanser 1983.

[0030] Furthermore, polypropylene materials with molecular weights of10,000 g/mol to 1,000,000 g/mol, which can be manufactured according toknown processes, Ullmann (5.) A.10, pages 615 and following pages,Houben-Weyl E20/2, pages 722 and following pages, Ullmann (4.) 19, pages195 and following pages, Kirk-Othmer (3.) 16, pages 357 and followingpages.

[0031] However, it is also possible to use copolymerisates of the abovementioned olefins, or those with further alpha-olefins, such as—forexample—polymers of ethylene with butylene, hexene and/or octene, EVA(ethylene vinyl acetate copolymerisate), EBA (ethylene ethyl acrylatecopolymerisate), EEA (ethylene butyl acrylate copolymerisate), EAS(acrylate ethylene copolymerisate), EVK (ethylene vinyl carbazolcopolymerisate), EPB (ethylene propylene block copolymers), EPDM(ethylene propylene diene copolymerisate), PB (polybutylene), PMP(polymethyl pentene), PIB (poly isobutylene), NBR (acryl nitrilebutadiene copolymerisate), polyisoprene, methyl-butylene copolymerisate,isoprene isobutylene copolymerisate.

[0032] Manufacturing methods: such polymerisates are, for example,published in the Kunststoff-Handbuch (=Plastics Manual), Volume IV,Munich, Hanser Verlag, Ullmann (4.) 19, pages 167 and following pages,Winnacker-Kückler (4.) 6, 353 to 367, Elias & Vohwinkel, Neue PolymereWerkstoffe, (=New Polymer Materials), Munich, Hanser 1983, Franck &Biederbick, Kunststoff Kompendium Würzburg (=Würzburg PlasticsCompendium), Vogel 1984.

[0033] Suitable thermoplastic synthetics according to the inventioninclude thermoplastic and aromatic polycarbonates, particularly thosebased on diphenols of Formula (1)

[0034] where

[0035] A can be a single bond, C₁-C₅-alkylene, C₂-C₅-alkylidenes,C₅-C₆-cycloalkylidenes, —S—, —SO₂—, —O—, —CO—, or a C₆-C₁₂-aryleneresidue, which may as appropriate be compensated with aromatic ringscontaining hetero atoms,

[0036] residue B refers to the following, independent of each other,C₁-C₈-alkyl, C₅-C₁₀ aryl, with particular preference to phenyl,C₇-C₁₂-aralkyl, preferably benzyl, halogen, preferably chlorine,bromine,

[0037] x independent of each other: 0, 1 or 2 and

[0038] p signifies 1 or 0.

[0039] or alkyl-substituted dihydroxy phenyl cyclo-alkanes of Formula(II),

[0040] where

[0041] R¹ and R², independent of each other, are hydrogen, halogen,preferably chlorine or bromine, C₁-C₈ alkyl, C₅-C₆ cyclo-alkyl, C₆-C₁₀aryl, preferably phenyl, and C₇-C₁₂ aralkyl, preferably phenyl-C₁-C₄alkyl, particularly benzyl,

[0042] m is an integer from 4 to 7, preferably 4 or 5.

[0043] R³ and R⁴ for each individually selectable value of Z, hydrogenor C₁-C₆ alkyl, preferably hydrogen, methyl or ethyl.

[0044] and

[0045] Z relates to carbon, with the provision that on at least one atomR³ and R⁴ simultaneously signify alkyl.

[0046] Suitable diphenols as per Formula (I) are, for example,hydroquinone, resorcin, 4,4′-dihydroxydiphenyl,2,2-bis-(4-hydroxyphenyl)-propane, 2,4-bis-(4 hydroxyphenyl)-2-methylbutane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane,2,2-bis-(3-chloro-4-hydroxyphenyl)-propane,2,2-bis-(3.5-dibromo-4-hydroxyphenyl)-propane.

[0047] Preferred diphenols as per Formula (I) are2,2-bis-(4-hydroxyphenyl)-propane, 2,2bis-(3,5-dichloro-4-hydroxyphenyl)-propane and1,1-bis-(4-hydroxyphenyl)-cyclohexane.

[0048] Preferred diphenols of Formula (II) aredihydroxydiphenylcyclo-alkanes with 5 and 6 ring C-atoms in thecycloaliphatic residue [(m=4 or 5 in Formula (II)], such as—forexample—diphenols of the following formulae:

[0049] where 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexyne(Formula IIc) is particularly preferred.

[0050] Polycarbonates which are suitable under the invention can bebranched as known, preferably by integration of 0.05 to 2.0% molecular,in relation to the total of employed diphenols, on triple-function ormore than triple-function compounds, e.g. those with three or more thanthree phenolic groups, for example:

[0051] Phloroglucinol,

[0052] 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene-2,

[0053] 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene,

[0054] 1,3,5-tri-(4-hydroxyphenyl)-benzol

[0055] 1,1,1-tri-(4-hydroxyphenyl)-ethane,

[0056] Tri-(4-hydroxyphenyl)-phenylmethane,

[0057] 2,2-bis-(4,4-bis-(4-hydroxyphenyl)-cyclohexyl)-propane,

[0058] 2,4-bis-(4-hydroxyphenyl)-isopropyl) phenol,

[0059] 2,6-bis-(2-hydroxy-5′-methyl-benzyl)-4-methylphenol,

[0060] 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenol)-propane,

[0061] Hexa-(4-(4-hydroxyphenyl-isopropyl)-phenyl)-ortho-terephthalicacid resin,

[0062] Tetra-(4-hydroxyphenyl)-methane,

[0063] Tetra-(4-(4-hydroxyphenyl-isopropyl)-phenoxy)-methane and

[0064] 1,4-bis-((4′-,4″-dihydroxytriphenyl)-methyl)-benzol.

[0065] Some of the other triple-functional compounds are2,4-dihydroxybenzoe acid, trimesic acid, trimellitic acid, cyanuricchloride and 3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindol.

[0066] Preferred polycarbonates are, in addition tobisphenol-A-homopolycarbonate the copolycarbonates of bisphenol. A withup to 15 molecular % in relation to the molecular totals of diphenols,of 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane.

[0067] The employed aromatic polycarbonates can partially be replaced byaromatic polyester carbonates.

[0068] Aromatic polycarbonates and/or aromatic polyester carbonates canbe manufactured as known in literature on the subject or according toprocesses known in literature on the subject (refer, for examples ofmanufacture of aromatic polycarbonates, Schnell “Chemistry and Physicsof Polycarbonates”, Interscience Publishers, 1964 and DE-AS 1 495 626,DE-OS 2 232 877, DE-OS 2 703 376, DE-OS 2 714 544, DE-OS 3 000 610,DE-OS 3 832 396; and, for production of aromatic polyester carbonates,for example, DE-OS 3 077 934).

[0069] Aromatic polycarbonates and/or aromatic polyester carbonates can,for example, be manufactured by conversion of diphenols with carbonichalides, preferably phosgene and/or with dicarbonic dihalides,preferably benzol dicarbonic halides, in accordance with the interphasemethod, where appropriate including the use of chain-breakers andpossibly involving triple-functional or more than triple-functionalbranching agents.

[0070] Furthermore, styrene copolymerisates of one or at least twoethylene unsaturated monomers (vinyl monomers) are suitable asthermoplastic synthetics, such as, for example, those of styrene,alpha-methyl styrene, atomic-substituted styrenes, acryl nitrile,methacryl nitrile, methyl methacrylate, maleic anhydride, N-substitutedmaleinimides and (meth)acrylate esters with 1 to 18 C-atoms in thealcohol component.

[0071] Copolymerisates are resinous, thermoplastic and rubber-free.

[0072] Preferred styrene-copolymerisates are those made of at least onemonomer from the range of styrene, alpha-methyl styrene and/oratomic-substituted styrene with at least one monomer from the range ofacryl nitrile, methacryl nitrile, methyl methacrylate, maleic acidanhydride and/or N-substituted maleinimide.

[0073] Particularly preferred weight relationships in thermoplasticcopolymerisate are 60 to 95% by weight of styrene monomers and 40 to 5%by weight of the other vinyl monomers.

[0074] Particularly preferred copolymerisates are those of styrene withacryl nitrile and, where appropriate, with methyl methacrylate, fromalpha-methyl styrene with acryl nitrile and, where appropriate, withmethyl methacrylate, or from styrene and alpha-methyl styrene with acrylnitrile and, where appropriate, with methyl methacrylate.

[0075] Styrene-acryl nitrile copolymerisates are known and can beproduced by radical polymerisation, particularly by emulsion,suspension, solution or mass polymerisation. Copolymerisates preferablyhave molecular weights M_(w) (weighting averages, to be determined bylight scatter or sedimentation) of between 15,000 and 200,000 g/mol.

[0076] Particularly preferred copolymerisates are also statisticallyconstructed copolymerisates of styrene and maleic anhydride, which canpreferably be produced by a continuous mass or solution polymerisationin the case of incomplete conversions from the corresponding monomers.

[0077] The proportions of both components of statistically constructedstyrene maleic acid anhydride copolymers which experience shows to besuitable can be varied within wide limits. The preferred content ofmaleic acid anhydride is 5 to 25% by weight.

[0078] In place of styrene it is possible for polymers also to containatomic substituted styrenes such as p-methyl styrene, 2,4-dimethylstyrene and other substituted styrenes such as alpha-methyl styrene.

[0079] Molecular weights (numerical average M_(n)) of styrene maleicacid anhydride copolymers may vary over a wide range. Preference isgiven to the range of 60,000 to 200,000 g/mol. A preferred limitviscosity for these products is 0.3 to 0.9 (measured in dimethylformamide at 25° C.; in this instance refer to Hoffmann, Krömer, Kuhn,Polymeranalytik I (Polymer Analysis I), Stuttgart, 1977, pages 316 andfollowing pages).

[0080] Graft copolymerisates are also suitable as thermoplasticsynthetics. These include graft copolymerisates with rubber-elasticcharacteristics which can be obtained from at least two of the followingmonomers: chloroprene, butadiene-1,3, isopropene, styrene, acrylnitrile, ethylene, propylene, vinyl acetate and (meth)-acrylate esterwith 1 to 18 C-atoms in the alcohol component; i.e. polymerisates, asdescribed, for example, in “Methoden der Organischen Chemie” (OrganicChemistry Methods) (Houben-Weyl), volume 14/1, Georg Thieme-Verlag,Stuttgart 1961,pages 393-406 and in C. B. Bucknall, “ToughenedPlastics”, Appl. Science Publishers, London 1977. Preferred graftpolymerisates are partially interlinked and have gel contents of morethan 20% by weight, preferably over 40% by weight, and particularly over60% by weight.

[0081] Preferred graft copolymerisates to be used are, for example,copolymerisates from styrene and/or acryl nitrile and/or (meth)-acrylatealkyl esters grafted on polybutadiene, butadiene/styrene copolymerisatesand acrylate rubbers; i.e. copolymerisates of the type described inDE-OS 1 694 173 (=U.S. Pat. No. 3,564,077); polybutadienes,butadiene/styrene or butadiene/acryl nitrile copolymerisates,polyisobutenes or polyisoprenes, grafted with acrylate or methacrylatealkyl esters, vinyl acetates, acryl nitrile, styrene and/or alkylstyrenes, as described, for example, in DE-OS 2 348 377 (=U.S. Pat. No.3,919,353).

[0082] Particularly suitable polymerisates are, for example, ABSpolymerisates such as are described, for example, in DE-OS 2 035 390(=U.S. Pat. No. 3,644,574) or in DE-OS 2 248 242 (=GB-PS 1 409 275).

[0083] Graft copolymerisates can be manufactured in accordance withknown processes such as mass, suspension, emulsion or mass/suspensionprocesses.

[0084] It is possible to use, as thermoplastic polyamides, polyamide 66(polyhexamethylene adipine amide) or polyamides of cyclic lactams with 6to 12 C-atoms, preferably from lauric lactam and particularly preferablyeta-caprolactam-polyamide 6 (polycaprolactam) or copolyamides with mainconstituents 6 or 66, or mixes with the main constituent of the saidpolyamides. Preference goes to polyamide 6 manufactured by activatedanionic polymerisation or copolyamide manufactured by activated anionicpolymerisation, whose main constituent is polycaprolactam.

[0085] The reservoir coating contains a freely moveable repellent agent.The proportion of repellent agent in relation to the reservoir coatingparticularly amounts to 0.001% volume to 99% volume, preferably of0.005% volume and 50% volume, particularly preferably of 0.01% volumeand 10% volume and especially preferably of 0.1% volume and 5% volume.

[0086] Surface-active compounds of any molecular weight must be regardedas water-repellent and/or oil-repellent agents. These compounds arepreferably cationic, anionic, amphoteric or non-ionic surface activecompounds, such as those listed in the index of “Surfactants Europa, ADictionary of Surface Active Agents available in Europe, edited byGordon L. Hollis, Royal Society of Chemistry, Cambridge, 1995.

[0087] The following can be mentioned as examples of anionic repellentagents: alkyl sulphates, ether sulphates, ether carboxylates, phosphateesters, sulfosuccinate, sulfosuccinatamides, paraffin sulphonates,olefin sulphonates, sarcosinates, isothionates, taurates and ligninbonds.

[0088] Quaternary alkyl ammonium compounds and imidazole can bementioned as examples of cationic repellent agents.

[0089] Examples of amphoteric repellent agents are: betaine, glycinate,propionate and imidazole.

[0090] Examples of non-ionic repellent agents are: alkoxylates,alkyloamides, ester, amine oxides and alkypolyglycosides. Other productsof conversion of alkylene oxides with alkylatable compounds, such asaliphatic alcohols, aliphatic amines, aliphatic acids, phenols, alkylphenols, aryl alkyl phenols, such as styrene phenol condensates,carbonic acid amides and resin acids are also relevant.

[0091] Particular preference is given to repellent agents in respect ofwhich there is 1-100% replacement of hydrogen atoms by fluorine atoms,particular preference being given to those with 60-95% substitution.Some examples are: perfluorated alkyl sulphate, perfluorated alkylsulphonate, perfluorated alkyl phosphonate, perfluorated alkylphosphinate and perfluorated carbonic acids.

[0092] Preference is given, for purposes of polymeric repellent agents,to the water-repellent coating, or, as a polymeric water-repellentmaterial for the surface, to compounds with a molecular weight of M_(w)of >500 to 1,000,000, preferably 1,000 to 500,000 and particularlypreferably 1,500 to 20,000. These polymeric repellent agents can benon-ionic, anionic, cationic or amphoteric compounds.

[0093] Furthermore, these polymeric repellent agents can behomopolymerisates and copolymerisates, graft polymerisates and graftcopolymerisates and statistical block polymers.

[0094] Particular preference goes to polymeric repellent agents of theAB, BAB and ABC block polymer type. Amongst AB or BAB block polymers,the A segment is a hydrophilic homopolymer or copolymer, and the B-blockis a water-repellent homopolymer or copolymer or a salt thereof.

[0095] Particular preference is also given to anionic, polymericrepellent agents, particularly products of condensation of aromaticsulphonic acids with formaldehyde and alkyl naphthalene sulphonic acidsor those of formaldehyde, naphthalene sulphonic acids and/or benzolsulphonic acids, products of condensation from similarly substitutedphenol with formaldehyde and sodium bisulphite.

[0096] Furthermore, preference is given to products of condensationwhich can be obtained by conversion of naphthols with alkanols,additions of alkylene oxide and at least partial transfer of terminalhydroxy groups to sulpho groups or semi-esters of maleic acid andphthalic acid or succinic acid.

[0097] In a different preferred specification of the process under thisinvention, the repellent agent is obtained from the group ofsulpho-succinate esters and alkyl benzol sulphonates. Preference alsogoes to sulphated, alkoxylated aliphatic acids or their salts.Alkoxylated aliphatic acid alcohols are in particular those C₆-C₂₂aliphatic alcohols which have 5 to 120 ethylene oxides, those with 6 to60, and especial preference goes to those with 7-30 ethylene oxides, thealcohols being saturated or non-saturated, with particular reference tostearyl alcohol. Sulphated alkoxylated aliphatic alcohols are presentpreferably as a salt, in particular as alkaline or amine salts,preferably as diethyl amine salts.

[0098] The covering coating consists in particular of a metal oxide,metal carbide, metal nitride, metal sulphide, metal fluoride or acompound of these materials.

[0099] Particular preference goes to the metal, for the metal compoundof the covering coating, from the range of: beryllium, magnesium,scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel,copper, zinc, gallium, yttrium, zircon, niobium, molybdenum, technetium,ruthenium, rhenium, palladium, silver, cadmium, indium, tin, lanthanum,cerium, praseodymium, neodymium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium,hafnium, tantalum, wolfram, rhenium, osmium, iridium, platinum, gold,thallium, lead, bismuth, and in particular titanium, aluminium,magnesium, nickel or an alloy of the above mentioned metals.

[0100] Particular preference goes to generation of the covering coatingby vaporisation or atomisation of the said coating materials, withdeposition on the reservoir coating.

[0101] As a similarly preferred preference, the surface of the coveringcoating exhibits a surface topography as described in the internationalpatent application of case reference PCT/99/10322. In this context,surface topography is constructed such that the value of the integral ofa function S

S(log f)=a(f)·f

[0102] which states a relationship between local frequencies f of theindividual Fourier components and their amplitudes a(f), betweenintegration limits log(f₁/μm⁻¹)=−3 and log(f₂/μm⁻¹)=3, is at least 0.3.

[0103] In this case, the boundary angle in relation to water is markedlyhigher than that of a non-structured, flat surface.

[0104] For surfaces according to the invention, there is a wide range oftechnical possibilities for applications. Consequently, the subject ofthis invention also relates to the following applications ofrepellent-treated surfaces under the invention:

[0105] In the case of transparent materials, repellent-treated surfacescan be used as the window or as the covering coating of transparentwindows, in particular glass or plastic windows, particularly those ofsolar cells, vehicles, aircraft or houses.

[0106] A further utilisation is for frontage components on buildings, inorder to protect them from wet.

[0107] Below, we explain the invention in the light of figures andexamples.

[0108] The following figures illustrate:

[0109]FIG. 1 cross-section of surface

[0110]FIG. 1a an enlarged extract from the surface as per FIG. 1

EXAMPLE

[0111] 1. Production of Reservoir Coating

[0112] The mixture of

[0113] 30 g o-trifluoro methyl styrene

[0114] 70 g Zonyl-TA-N (compound of formula: C₉F₁₉CH₂CH₂O—CO—C(CH₃)═CH₂)

[0115] 1 g azo bis isobutyronitrile and

[0116] 100 g methyl isobutyl ketone

[0117] is dripped for 2 hours at 90° C. into a flask, and the mixture isstirred for 16 hours. Next, the mixture is heated to 120° C. for 1 hour.Next, 1 g of Zonyl alcohol [C₉F₁₉CH₂CH₂OH] of diffusing repellent agentis added to the mix.

[0118] A glass panel 4 mm thick serves as the substrate 1. Using afilm-drawing frame, a surface of 50×50 mm² of the glass panel is coatedwith a wet film thickness of 200 μm and dried for 24 hours at 80° C.

[0119] 2. Production of Covering Coating 3

[0120] Reservoir coating 2 was applied by electron gun vaporisation at asubstrate temperature of 353K, a rate of 0.35 nm/s at a pressure of1×10⁻⁴ mbar with a 1 μm thick ZrO₂ coating.

[0121] 3. Production of Pores 4

[0122] The production of pores 4 in covering coating 3 is performed bylaser ablation with a pulsed UV laser at 193 nm with pulsing power of 4J/cm² pulses. Recourse is had to an ArF Excimer Laser, of the Lambda1000 Type from Lambda Physik. The beam section of approximately 20 μmdiameter was generated by an aperture.

[0123] Using this device, at a repetition frequency of 20 Hz with 10pulses, the hole 4 illustrated in FIG. 1a, in covering coating 3 ofdiameter 20 μm is produced. Overall, 4×4 pores 4 were introduced oncovering coating 3 at a distance between adjacent pores 4 of 10 mm.

[0124] Next, the correspondingly produced specimen is kept heated for 24hours at 100° C.

[0125] The water boundary angle of the achieved surface, afterproduction, is 132°. Analysis of outer coating 5 of the surface wasperformed using x-ray photo-electron spectroscopy (XPS) withpolychromatic MgKα excitation at 0° electron output angle over a surfaceof a diameter of approximately 150 μm. Surface analysis produced arelative fluorine component of 52% atomic. In addition, a proportion of1.0% atomic Zr, 41% atomic C and 5% atomic O was certified. Under theemployed analysis conditions, this Zr proportion indicates a coatingthickness of the water-repellent film of the order of magnitude of 5 nm(refer to the following work in relation to this method of analysis: D.Briggs, M. P. Seah, Practical Surface Analysis, Vol. 1, Wiley,Chichester, 1990).

[0126] To test the durability of the coating, outer coating 5 isentirely removed by ion bombardment with Ar ions with power of 500 eVover a surface of 10×10 mm². After ion bombardment, no further fluorinecould be found on the bombarded surface. XPS analysis indicates a pureZrO₂ coating. After bombardment, the water boundary angle was only 30°.In the course of a day, however, the surface composition once againchanged to the values which were present before ion bombardment, and thewater boundary angle increased to 130°. Accordingly, outer coating 5 isself-sustaining.

[0127] The proportion of dissolved repellent agent Zonyl alcoholC₉F₁₉CH₂CH₂OH present in reservoir coating 2, of 1%, is adequate, withregard to the coating thickness of outer coating 5, of approximately 5nm, for approximately 200 total replacements of water-repellent outercoating 5. With a weathering period under normal conditions ofapproximately one month, the useful life of the outer coating and thestability of the boundary angle can therefore be predicted to be about17 years.

1. Long-term stable water-repellent or oil-repellent surface made up atleast of a substrate (1) with a reservoir coating (2) arranged thereoverand containing a repellent agent, a covering coating (3) arrangedthereover and having pores (4) or being permeable to the repellentagent, and an outer coating (5) which is made up of the repellent agent.2. Surface as claimed in claim 1, characterised in that the outersurface of covering coating (3) exhibits a surface topography which isconfigured such that the value of the integral of a function S S(logf)=a(f)·f which states a relationship between local frequencies f of theindividual Fourier components and their amplitudes a(f), betweenintegration limits log(f₁/μm⁻¹)=−3 and log(f₂/μm⁻¹)=3, is at least 0.3.3. Surface as claimed in claim 1 or 2, characterised in that thereservoir coating (2) exhibits a coating thickness in the range of 0.1μm to 10,000 μm, preferably in the range of 1 μm to 2,000 μm,particularly preferably in the range of 10 μm to 1,000 μm and quiteespecially preferably in the range of 50 μm to 500 μm.
 4. Surface asclaimed in any one of claims 1 to 3, characterised in that the coveringcoating (3) exhibits a coating thickness in the range of 0.01 μm to 100μm, preferably in the range of 0.02 μm to 50 μm, particularly preferablyin the range of 0.05 μm to 20 μm and quite especially preferably in therange of 0.1 μm to 10 μm.
 5. Surface as claimed in any one of claims 1to 4, characterised in that the pores (4) exhibit a cylindrical orconical form in transverse section along their longitudinal axis. 6.Surface as claimed in any one of claims 1 to 5, characterised in thatthe aperture section of the pores (4) at the boundary surface to thereservoir coating (2), which may independently be the same or differentat the boundary surface in relation to the outer coating, is from 10⁻⁵μm² up to 10⁶ μm², preferably of 4×10⁻⁴ μm² to 4×10⁴ μm², particularlypreferably from 1×10⁻² μm² up to 1×10⁴ nm² and quite exceptionallyadvantageously from 2×10⁴ μm² to 2×10³ μm².
 7. Surface as claimed in anyone of claims 1 to 6, characterised in that the quantity of pores (4)per unit surface area is from 2 mm⁻² to 10⁻⁴ mm⁻², and preferably 1 mm⁻²to 10⁻³ mm⁻², with particular preference for 0.5 mm⁻² to 10⁻² mm⁻². 8.Surface as claimed in any one of claims 1 to 7, characterised in thatthe pores (4) are preferably produced by ablation with lasers,particularly preferably by ultra violet laser, and with especiallyparticular preference for ultra violet laser of wavelengths 308 nm, 266nm, 248 nm, 213 nm, 193 nm or 157 nm.
 9. Surface as claimed in any oneof claims 1 to 8, characterised in that the substrate (1) consists of atransparent material, particularly transparent glass, plastic orceramics.
 10. Surface as claimed in any one of claims 1 to 9,characterised in that the reservoir coating (2) is an open/porouscoating of metal or an open/porous coating of a ceramic material orconsists of a duroplastic or thermoplastic material, preferably atransparent material, and preferably a transparent glass, plastic orceramic.
 11. Surface as claimed in any one of claims 1 to 10,characterised in that the proportion of the repellent agent in relationto reservoir coating (2) is of 0.001% volume to 99% volume, preferablyof 0.005% volume and 50% volume, particularly preferably of 0.01% volumeand 10% volume and quite especially preferably of 0.1% volume and 5%volume.
 12. Surface as claimed in any one of claims 1 to 10,characterised in that the covering coating (3) consists of a metaloxide, metal carbide, metal nitride, metal sulphide, metal fluoride or acombination of these materials.
 13. Use of a surface as claimed in anyone of claims 1 to 12 for frontage components of buildings.
 14. Use of asurface as claimed in any one of claims 1 to 12 with a coatingconstruction of transparent materials as a panel or as a coveringcoating of transparent panels, particularly glass or plastic panels,being particularly preferred for solar cells, vehicles, aircraft orbuildings.